Figure 4.

Resveratrol-treated dendritic cells (DCs) are poor stimulators of allogeneic CD4⁺ T cells. DCs were prepared as described in the Materials and methods and in some cultures resveratrol was added at various concentrations (from 3 to 50 μm), depending on the experiment. Treated DCs and controls were used to stimulate allogeneic T cells for 4 days, when [³H]thymidine was added for 18 hr, and proliferation was measured by liquid scintillation counting on day 5. (a) Resveratrol can greatly suppress the ability of lipopolysaccharide (LPS)-activated DCs to stimulate CD4⁺ T cells in mixed lymphocyte reactions (MLRs) when added at t = 0, as described above. At 50 μm concentrations, DCs were approximately four times less capable of inducing proliferation in responding T cells compared with controls (P < 0·0001). (b) Control DCs and DCs treated just prior to maturation were used as stimulators. Resveratrol suppressed the stimulatory capacity of DCs but only by about 40% in comparison to cases where it was already present during DC differentiation. Data represent the mean ± standard deviation of three independent experiments. *, P ≤ 0·05; **, P ≤ 0·01; ***, P ≤ 0·001 (Student’s t-test for independent samples).